XPath testbed for REST plugin

The REST plugin metadata XML file uses XPath to describe the basexpath and fieldxpath for output parameters (to identify a nodes location within the response structure).

A good tool for helping write/confirm the XPath is the XPath Expression Testbed: http://www.whitebeam.org/library/guide/TechNotes/xpathtestbed.rhtm . The tool allows one to upload a response XML, enter in an XPath expression, and will highlight the corresponding nodes .